#include <stdio.h>
#include <string.h>

int main() {
    char str[] = "hello world";
    char substr[] = "world";
    char *ptr = strstr(str, substr);
    if (ptr != NULL) {
        printf("The substring \"%s\" is found at position %d in the string \"%s\".\n", substr, ptr - str, str);
    } else {
        printf("The substring \"%s\" is not found in the string \"%s\".\n", substr, str);
    }
    return 0;
}
